My test code is like this:

#!/usr/bin/perl
$code = 'if($a>$b){';
$code .= '$result = 1;}';

$a =1;
$b = 0;
$result =0;

eval $code;
print $@ if ($@);
print $result;

[download]
There are no information displayed on the screen. What's wrong with the code ?
thanks!

Update

To bmann:

yes,it is right.But I have another question:

#!/usr/bin/perl
$code  = 'if($port_a $cmp_op $port_b){$result=1;}';
$code .= 'else{$result=0;}';
$port_a =7777;
$port_b = 6666;
$cmp_op = ">";
eval $code;
print $@ if($@);
print $result; 
$perl eval
Scalar found where operator expected at (eval 1) line 1, near "$port_a
+ $cmp_op"
        (Missing operator before $cmp_op?)

[download]

So I can't use eval like that which I must specify operator not scalar,is it true ? Are there any solution to do this ? thanks!

In reply to How to use eval? by iwanthome

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